Any way to watch the US Open Tennis (either free of for a small fee)

My parents have asked me how they can watch the US Open tennis, most likely through a computer. Does anyone know if you can use a VPN to watch it, even if they had to pay a small fee? I thought they could watch it on ESPN online but I don't think that's possible.

On a side note, I subscribe to Sky and have Sky Sports, so can they use my Sky account to watch it online - I don't use any of the on-the-go things or apps, strictly just watch it on the box.

Any one have any ideas? I would massively appreciate if anyone could offer any assistance. Thanks in advance.